Coaxial cables comprise an inner conductor, an outer conductor concentrically disposed around the inner conductor and a non-conducting insulation uniformly disposed therebetween. The cables may or may not include an outer insulation. Coaxial cables are used in many applications where it is necessary to carry radio frequency or microwave frequency electrical signals. Coaxial cables often are employed in high vibration environments such as in ground, air or marine vehicles, weapons systems and many machines.
Coaxial cables must maintain their symmetry while in use. Variations in coaxial symmetry can create an impedance or a phase shift which can have a substantial degrading effect on the electrical signal carried by the cable. To maintain symmetry at an electrical connection, the ends of the coaxial cable typically are joined to coaxial cable connectors which are designed to have a minimum effect on the signal. Coaxial cable connectors may be used to join one cable to another or to join a coaxial cable to an electrical device. The connectors may take the form of a plug or a socket. Furthermore the connectors may be straight or angled relative to the axis of the cable.
The coaxial cable connector should be able to maintain a secure, high quality, radio frequency or microwave frequency connection in all environments in which the connector is used. More particularly, the coaxial cable connector should not permit either longitudinal or rotational movement of the cable relative to the connector despite forces exerted on either the cable or the connector.
One type of coaxial cable includes a center conductor, a symmetrical insulation, such as Teflon, surrounding the center conductor, and a semi-rigid tubular outer conductor, with no insulation extending around the tubular outer conductor. These semi-rigid tubular outer conductor coaxial cables can be joined to coaxial cable connectors by soldering. Although soldered connections are widely used, they present several significant problems. Specifically to make the soldered connection, both the tubular outer conductor and the connector must be heated sufficiently to cause the solder to melt and wick into the area between the two members. This heat causes the insulation to expand, and the expansion can cause a permanent deformation of the tubular outer conductor, with a resultant detrimental effect on the signal-carrying performance of the coaxial cable. In extreme instances the heat generated to melt the solder can damage nearby electrical components.
Solderless connectors for tubular outer conductor coaxial cables avoid problems attributable to soldering heat. However, solderless connectors have required a mechanical deformation of the outer conductor. For example, the cable may be inserted into a bushing or sleeve which then is placed in a special tool which crimps both the sleeve and the cable sufficiently to mechanically interengage the two. The crimped sleeve then can be force fit into another part of the connector. This deformation of the outer conductor has a substantial detrimental effect on the signal carried by the cable. If the connector is to be used in an environment with severe temperature, shock and vibration conditions, the size of the crimp must be further increased with an even greater degrading effect on electrical performance.
Other solderless coaxial connectors have been developed which rely on substantial compression rather than crimping. However, the net effect is the same in that the geometry of the cable changes with a resultant effect on electrical performance. The available crimping and compression solderless connectors require special tools to mechanically deform the outer conductor of the cable. These tools typically are quite expensive, and if not used properly can twist and permanently damage the cable. Additionally, crimping, compression and soldering all are permanent conditions. Thus it is difficult or impossible to disconnect, shorten and reconnect the cable in order to achieve a desired precise phase length.
Solderless connectors that avoid crimping and that avoid or minimize compression have been developed. However, the prior art connectors of this type have not provided a high quality RF or microwave frequency connection in all environments and have exhibited a tendency to move either axially or rotationally in response to external forces of vibrations. Certain prior art coaxial connectors have included gripping members that twist helically when compressed, thereby altering symmetry and electrical performance. Still other solderless coaxial connectors are costly to manufacture and/or include a large number of parts, thereby making assembly difficult.
In view of the above it is an object of the subject invention to provide a connector for semi-rigid tubular outer conductor coaxial cables which does not require soldering or other application of heat to the cable or the connector.
It is another object of the subject invention to provide a solderless coaxial connector for tubular outer conductor coaxial cables which does not require special tools and can be connected by hand or with a standard wrench.
It is an additional object of the subject invention to provide a solderless coaxial connector for tubular outer conductor coaxial cables which does not significantly affect the electrical performance at radio frequency or microwave frequency.
It is a further object of the subject invention to provide a solderless coaxial connector for tubular outer conductor coaxial cables which does not crimp or otherwise substantially deform the cable.
It is yet another object of the subject invention to provide a solderless coaxial connector for tubular outer conductor coaxial cables which can be easily disconnected and reconnected.
It is still an additional object of the subject invention to provide a solderless coaxial connector for tubular outer conductor coaxial cables which can be employed under severe conditions of temperature, shock, and vibration.
Another object of the subject invention is to provide a solderless coaxial connector which prevents axial and rotational movement relative to the cable.
Still another object of the subject invention is to provide a clamping sleeve for use with a solderless coaxial cable to securely grip the cable.